The dispensing apparatus of this invention has initial utility in the field of food product manufacturing and, in particular, has utility with respect to the preparation and forming of pizza. Pizza comprises a base shell of pastry material onto which various ingredients are placed and which include not only the meat and cheese products customarily applied, but invariably includes a tomato sauce that is first applied to the pizza shell prior to application of the other solid food ingredients. It is highly desirable that the tomato sauce be applied in a uniform thickness layer to obtain consistency in the quality of the product and in particular to obtain uniformity in the taste of a pizza throughout its entire extent.
Manufacturing of pizza on an assembly line basis such as in preparing large quantities for wholesaling as a frozen food product has resulted in development of various types of machines for application of the ingredients to the pastry shell forming the basic component of a pizza. Attempts have also been made to provide mechanized applicators for the tomato sauce that is initially applied to a pizza shell. One such mechanism that has been used is generally designated as a waterfall type dispenser. Such a dispenser comprises a feedplate having a surface which is oriented in a relatively steep incline and positioned above a conveyor along which the pizza shells will be transported in serial sequence. A roller device is provided to pick up the viscous tomato sauce from a reservoir and apply it to an upper end of the inclined feedplate. The feedplate has a transverse width which is substantially equal to the diameter of the pizza shells to which the sauce is to be applied. The sauce gravitates downwardy over the surface of the feedplate in a thin sheet toward the lower end from which it is discharged and deposited by gravity onto the pizza shell traversing the space beneath the feedplate. While a waterfall-type dispensing apparatus does perform the general objective of applying a viscous tomato sauce in a layer on the pizza shell, such apparatus has not been found fully satisfactory as it is incapable of applying the sauce in a uniform thickness layer. A primary reason for the waterfall-type dispensing apparatus failing to obtain the uniform thickness distribution is an inherent characteristic of viscous fluids. Tomato sauce is relatively viscous and as a consequence, even though it may be in a relatively uniform thickness sheet when flowing downwardly over the inclined surface of the feedplate, it tends to coagulate and form streams or rivulets as it flows off the discharge end which tend to concentrate the sauce and prevent it from flowing in a uniform thickness layer onto the pizza shell. Those streams are not of a continuous nature nor do they form at some fixed points across the transversely extending discharge end edge of the feedplate. The streams are of an intermittent nature resulting in indeterminate and varied lengths as well as variations in transverse spacing and cross-sectional size. Because of the viscous nature of the sauce, there is a cohesive characteristic exhibited with the sauce tending to hang onto the feedplate, thereby accentuating the irregularity of the conformations of the streams of sauce discharged with relatively large globules being formed at times. Consequently, the sauce is deposited on the pizza shell in dispersed concentrations which, even though they will tend to spread transversely over the shell's surface, will produce an uneven layer of non-uniform thickness.
Further complications in the mechanized application of tomato sauce to pizza shells is a result of the sauce products that are available. Different manufacturers produce sauces that have different viscosity characteristics, and thus, a manufacturer of pizza must continually monitor the operation of a sauce dispensing machine to assure that changes in the viscosity of the sauce do not seriously affect the deposit of the sauce onto the pizza. Even a same manufacturer may have variations in the viscosity of its own product as between different containers or batches of the sauce. Also, tomato sauces invariably include small particles of solid food products which may be from the tomatoes of which the sauce is manufactured or other food products incorporated in the sauce such as spices. Such solid food particles may also affect the flow characteristics of the sauce in an adverse manner and further destroy the uniformity in thickness of the layer of sauce from the feedplate onto the pizza shell.